U.S. patent application number 12/326443 was filed with the patent office on 2010-06-03 for indicia reading terminal having plurality of optical assemblies.
This patent application is currently assigned to Hand Held Products, Inc.. Invention is credited to Chen Feng, Colleen P. Gannon, William H. Havens, Jianhua Li, Ynjiun P. Wang.
Application Number | 20100133345 12/326443 |
Document ID | / |
Family ID | 42221890 |
Filed Date | 2010-06-03 |
United States Patent
Application |
20100133345 |
Kind Code |
A1 |
Havens; William H. ; et
al. |
June 3, 2010 |
INDICIA READING TERMINAL HAVING PLURALITY OF OPTICAL ASSEMBLIES
Abstract
There is described an indicia reading terminal having an image
sensor array including a plurality of pixels, a first optical
assembly for focusing imaging light rays onto a first set of pixels
of an image sensor array and a second optical assembly for focusing
imaging light rays onto a second set of pixels of the image sensor
array. The indicia reading terminal can be adapted to process image
data corresponding to pixels of the image sensor array for
attempting to decode a decodable indicia.
Inventors: |
Havens; William H.;
(Syracuse, NY) ; Feng; Chen; (Snohomish, WA)
; Gannon; Colleen P.; (Jordan, NY) ; Li;
Jianhua; (Fremont, CA) ; Wang; Ynjiun P.;
(Cupertino, CA) |
Correspondence
Address: |
HONEYWELL/MARJAMA;Patent Services
101 Columbia Road, P.O.Box 2245
Morristown
NJ
07962
US
|
Assignee: |
Hand Held Products, Inc.
Skaneateles Falls
NY
|
Family ID: |
42221890 |
Appl. No.: |
12/326443 |
Filed: |
December 2, 2008 |
Current U.S.
Class: |
235/472.01 |
Current CPC
Class: |
G06K 7/10722
20130101 |
Class at
Publication: |
235/472.01 |
International
Class: |
G06K 7/10 20060101
G06K007/10 |
Claims
1. An indicia reading terminal comprising: a two dimensional image
sensor array extending along an image plane, said two dimensional
image sensor array comprising a plurality of pixels; a hand held
housing encapsulating said two dimensional image sensor array; a
first optical assembly having a center optical axis and an imaging
lens, said first optical assembly for focusing imaging light rays
onto a first set of pixels of said two dimensional image sensor
array, wherein said imaging light rays transmitted by said first
optical assembly are transmitted about said center optical axis of
said first optical assembly, and wherein said first optical
assembly is adapted so that said center optical axis of said first
optical assembly is essentially unfolded; a second optical assembly
having a center optical axis and an imaging lens, said second
optical assembly for focusing imaging light rays onto a second set
of pixels of said two dimensional image sensor array, wherein said
imaging light rays transmitted by said second optical assembly are
transmitted about said center optical axis of said second optical
assembly, and wherein said second optical assembly includes an
optical surface that folds said center optical axis of said second
optical assembly by an angle of more than 10 degrees; a memory
capable of storing a frame of image data, said frame of image data
representing light incident on said image sensor array; and a CPU
capable of addressing said memory, wherein said CPU is adapted to
attempt to decode a decodable indicia represented in said frame of
image data.
2. The indicia reading terminal of claim 1, wherein said imaging
lens of said first optical assembly has a shorter focal length than
said imaging lens of said second optical assembly.
3. The indicia reading terminal of claim 1, wherein said indicia
reading terminal is adapted so that a field of view defined by said
first optical assembly in combination with said image sensor array
when said indicia reading terminal is at a certain terminal to
target distance is larger than a field of view defined by said
second optical assembly in combination with said image sensor array
when said indicia reading terminal is at said certain terminal to
target distance.
4. The indicia reading terminal of claim 1, wherein said first
optical assembly has a shorter best focus distance than said second
optical assembly.
5. The indicia reading terminal of claim 1, wherein said first
optical assembly has a shorter best focus distance than said second
optical assembly, wherein said first optical assembly has a shorter
focal length than said second optical assembly, and wherein said
first and second optical assemblies are fixed assemblies such that
that said best focus distances and said focal lengths of said first
and second optical assemblies are fixed.
6. The indicia reading terminal of claim 1, wherein said first set
of pixels comprises a larger number of pixels than a number of
pixels of said second set of pixels.
7. The indicia reading terminal of claim 1, wherein a ratio of
pixels of said first set of pixels to said second set of pixels is
greater than 1.5.
8. The indicia reading terminal of claim 1, wherein said second
optical assembly includes a double folding prism disposed in an
optical path of said second optical assembly intermediate of said
imaging lens of said second optical assembly and said image sensor
array, the double folding prism folding said center optical axis of
said second optical assembly in at least two locations, said double
folding prism being adapted so that said center optical axis of
said second optical assembly extends from said image sensor array
at an angle that deviates from a normal angle by less than 10
degrees.
9. The indicia reading terminal of claim 1, wherein said second
optical assembly includes a double folding prism disposed in an
optical path of said second optical assembly intermediate of said
imaging lens of said second optical assembly and said image sensor
array, the double folding prism having at least two reflective
surfaces for bending said center optical axis of said second
optical assembly, said double folding prism being formed utilizing
one of a precision molding process and a precision grinding
process.
10. The indicia reading terminal of claim 1, wherein said indicia
reading terminal is capable of processing image data of said
certain frame for attempting to decode a 2D bar code symbol
representation, and wherein said indicia reading terminal is
operative so that a level of optimization for decoding of a 2D bar
code symbol representations is greater when said CPU processes
image data representing light incident on said first set of pixels
than when processing image data representing light incident on said
second set of pixels.
11. The indicia reading terminal of claim 10, wherein said indicia
reading terminal is restricted from operating according to an
algorithm for attempting to decode a 2D bar code symbol when
processing image data corresponding to said second set of
pixels.
12. The indicia reading terminal of claim 1, wherein said first
optical assembly defines with said image sensor array a first field
of view, wherein said second optical assembly defines with said
image sensor array a second field of view, and wherein said indicia
reading terminal is adapted so that said indicia reading terminal
projects an aiming pattern at a substantially fixed location in
relation to said second field of view though a range of terminal to
target distances ranging from a short range terminal to target
distance of about 130 mm to a long range terminal to target
distance of about 420 mm.
13. The indicia reading terminal of claim 1, wherein said first
optical assembly defines with said image sensor array a first field
of view and wherein said second optical assembly defines with said
image sensor array a second field of view, and wherein said indicia
reading terminal is adapted so that said indicia reading terminal
projects an aiming pattern substantially at a horizontally
extending centerline of said second field of view though a range of
terminal to target distances ranging from a short range terminal to
target distance of about 130 mm to a long range terminal to target
distance of about 420 mm.
14. The indicia reading terminal of claim 1, wherein said indicia
reading terminal is adapted so that said first set of pixels
includes a set of pixels extending across more than 50% of the rows
of said image sensor array and wherein said second set of pixels
includes a set of pixels extending across less than 50% of rows of
pixels of said pixels of image sensor array.
15. The indicia reading terminal of claim 1, wherein said second
optical assembly includes an optical surface that folds said center
optical axis of said second optical assembly by more than 30
degrees.
16. The indicia reading terminal of claim 1, wherein said indicia
reading terminal includes aiming pattern generator that projects an
aiming pattern substantially at a horizontally extending centerline
of a field of view defined by said first optical assembly in
combination with said image sensor array through a range of
terminal to target distances ranging from about 130 mm to 420
mm.
17. The indicia reading terminal of claim 1, wherein said indicia
reading terminal wherein said first optical assembly and said image
sensor array define a first field of view, and wherein said second
optical assembly and said image sensor array define a second field
of view, and wherein said terminal includes a first a first aiming
pattern generator and a second aiming pattern generator, the first
aiming pattern generator capable of projecting an aiming pattern
substantially at a horizontally extending centerline of said first
field of view through a range of terminal to target distances, the
second aiming pattern generator capable of projecting an aiming
pattern substantially at a horizontally extending centerline of
said second field of view through a range of terminal to target
distances.
18. The indicia reading terminal of claim 17, wherein said terminal
is operative so that at least one of said first and second aiming
pattern generators is activated responsively to a sensed
condition.
19. The indicia reading terminal of claim 1, wherein said first
optical assembly and said image sensor array define a first field
of view and wherein said second optical assembly and said image
sensor array define a second field of view, and wherein said
terminal includes an aiming pattern generator that projects an
aiming pattern substantially at a horizontally extending centerline
of said second field of view through a range of terminal to target
distances.
20. An indicia reading terminal comprising: a two dimensional image
sensor array extending along an image plane, said two dimensional
image sensor array comprising a plurality of pixels; a hand held
housing encapsulating said two dimensional image sensor array; a
first optical assembly defining in combination with said image
sensor array a first field of view, said first optical assembly
having a center optical axis and an imaging lens, the first optical
assembly for focusing imaging light rays onto a first set of pixels
of said two dimensional image sensor array, said first set of
pixels comprising more than 50% of pixels of said image sensor
array, wherein said imaging light rays transmitted by said first
optical assembly are transmitted about said first center optical
axis of said first optical assembly, and wherein said first optical
assembly is adapted so that said first center optical axis is
essentially unfolded; a second optical assembly defining in
combination with said image sensor array a second field of view,
said second optical assembly having a center optical axis and an
imaging lens, the second optical assembly for focusing imaging
light rays onto a second set of pixels of said two dimensional
image sensor array, said second set of pixels comprising less than
50% of pixels of said image sensor array, wherein said imaging
light rays transmitted by said second optical assembly are
transmitted about said center optical axis of said second optical
assembly, and wherein said second optical assembly includes an
optical element that folds said center optical axis of said second
optical assembly by an angle of more than 10 degrees, said second
optical assembly having a longer best focus distance than said
first optical assembly, said imaging lens of said second optical
assembly having a longer focal length than said imaging lens of
said first optical assembly; an aiming pattern generator including
a laser diode assembly, said aiming pattern generator projecting an
aiming pattern; a memory capable of storing a frame of image data,
said frame of image data having image data representing light
incident on said image sensor array; and a CPU capable of
addressing said memory, wherein said CPU is adapted to attempt to
decode a decodable indicia represented in said frame of image
data.
21. The indicia reading terminal of claim 20, wherein said aiming
pattern generator is adapted to project said aiming pattern
substantially at a horizontally extending centerline of said second
field of view through a range of terminal to target distances.
22. An indicia reading terminal comprising: a two dimensional image
sensor array extending along an image plane, said two dimensional
image sensor array comprising a plurality of pixels; a hand held
housing encapsulating said two dimensional image sensor array; a
first optical assembly having a center optical axis and an imaging
lens, said first optical assembly for focusing imaging light rays
onto a first set of pixels of said two dimensional image sensor
array, wherein said imaging light rays transmitted by said first
optical assembly are transmitted about said center optical axis of
said first optical assembly; a second optical assembly having a
center optical axis and an imaging lens, said second optical
assembly for focusing imaging light rays onto a second set of
pixels of said two dimensional image sensor array, wherein said
imaging light rays transmitted by said second optical assembly are
transmitted about said center optical axis of said second optical
assembly, and wherein said second optical assembly includes a
precision manufactured double folding prism for folding said center
optical axis of said second optical assembly at two locations, said
double folding prism being precision manufactured by one of an
injection molding process or an optical grinding process; a memory
capable of storing a frame of image data, said frame of image data
representing light incident on said image sensor array; and a CPU
capable of addressing said memory, wherein said CPU is adapted to
attempt to decode a decodable indicia represented in said frame of
image data.
23. The indicia reading terminal of claim 22, wherein said first
optical assembly is adapted so that said center optical axis of
said first optical assembly is essentially unfolded.
24. The indicia reading terminal of claim 22, wherein said second
optical assembly includes a longer best focus distance and a longer
focal length than said first optical assembly, and wherein said
indicia reading terminal is adapted so that a field of view defined
by said second optical assembly and said image sensor array is
defined, throughout a range of terminal to target distances from
about 130 mm to about 420 mm, at a location within a field of view
defined by said second optical assembly and said image sensor array
throughout a range of terminal to target distances from about 130
mm to about 420 mm.
Description
FIELD OF THE INVENTION
[0001] The invention relates to registers in general and in
particular to an optical based register.
BACKGROUND OF THE PRIOR ART
[0002] Indicia reading terminals are available in multiple
varieties. The well known gun style reader as commonly seen at
retail store checkout counters is typically available in a form
devoid of a keyboard and display. Enhanced functioning indicia
reading terminals having keyboards displays and advanced networking
communication capabilities are also available.
[0003] Users of indicia reading terminals whatever the variety have
long desired an increase in working range (a measure of a
terminal's capacity to decode decodable indicia at a wide range of
terminal to target distances). Various proposals have been made for
increasing a terminal's working range. Approaches in the prior art
have been based on optical design, analog signal processing,
digital signal processing and on combinations of the above.
However, designs for increased working range have often resulted in
high cost, significantly increased complexity in manufacturability,
reduced reliability and reduced durability.
[0004] There remains a need for an increased working range indicia
reading terminal that is of low cost, is easy to manufacture,
reliable and durable.
SUMMARY OF THE INVENTION
[0005] There is described an indicia reading terminal having an
image sensor array including a plurality of pixels, a first optical
assembly for focusing imaging light rays onto a first set of pixels
of an image sensor array and a second optical assembly for focusing
imaging light rays onto a second set of pixels of the image sensor
array. The indicia reading terminal can be adapted to process image
data corresponding to pixels of the image sensor array for
attempting to decode a decodable indicia.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The features described herein can be better understood with
reference to the drawings described below. The drawings are not
necessarily to scale, emphasis instead generally being placed upon
illustrating the principles of the invention. In the drawings, like
numerals are used to indicate like parts throughout the various
views.
[0007] FIG. 1 is a side cross sectional view of an indicia reading
terminal imaging module in an illustrative embodiment having a
first optical assembly and a second optical assembly;
[0008] FIG. 2 is a block diagram illustrating exemplary hardware
components which can be incorporated in an indicia reading terminal
as described herein;
[0009] FIG. 3 is a top view of an image sensor array having a first
set of pixels and a second set of pixels;
[0010] FIG. 4 is an exploded perspective view of an imaging module
in one embodiment;
[0011] FIG. 5 is an assembled perspective view of an imaging module
as shown in FIG. 4;
[0012] FIG. 6 is a perspective view of an indicia reading terminal
in one embodiment including a hand held housing that encapsulates
an imaging module;
[0013] FIG. 7 is a perspective view of a double folding prism with
hidden lines shown that can be precision manufactured in one
embodiment;
[0014] FIG. 8 is a side view illustrating relationships between
fields of view associated with first and second optical assemblies
in one embodiment;
[0015] FIG. 9 is an illustration of a set of fields of view defined
on a target substrate by first and second optical assemblies and an
image sensor array at a first, shorter terminal to target distance
where the terminal is adapted so that an aiming pattern is
projected substantially at a horizontally extending centerline of
the first field of view;
[0016] FIG. 10 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a second,
longer terminal to target distance where the terminal is adapted so
that an aiming pattern is projected substantially at a horizontally
extending centerline of a first field of view;
[0017] FIG. 11 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a first,
shorter terminal to target distance where the terminal is adapted
so that an aiming pattern is projected substantially at a
horizontally extending centerline of a second field of view;
[0018] FIG. 12 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a second,
longer terminal to target distance where the terminal is adapted so
that an aiming pattern is projected substantially at a horizontally
extending centerline of a second field of view;
[0019] FIG. 13 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a first,
shorter terminal to target distance where the terminal is adapted
so that an aiming pattern is projected substantially at
horizontally extending centerline of each of said first and second
fields of view;
[0020] FIG. 14 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a second,
longer terminal to target distance where the terminal is adapted so
that an aiming pattern is projected substantially at horizontally
extending centerline of each of said first and second fields of
view;
[0021] FIG. 15 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a first,
shorter terminal to target distance where the terminal is adapted
so that an aiming pattern is projected intermediate of horizontally
extending centerline of the first and second fields of view;
[0022] FIG. 16 is an illustration of a set of fields of view
defined on a target substrate by first and second optical
assemblies in combination with an image sensor array at a second,
longer terminal to target distance where the terminal is adapted so
that an aiming pattern is projected intermediate of horizontally
extending centerlines of first and second fields of view.
DETAILED DESCRIPTION OF THE INVENTION
[0023] A cross sectional side view of an exemplary imaging module
600 of indicia reading terminal 1000 in one embodiment is shown in
FIG. 1. Terminal 1000 can have a first optical assembly 10 and a
second optical assembly 20. Terminal 1000 can also have an image
sensor array 1033 including a plurality of pixels and can be
configured so that first optical assembly 10 focuses imaging light
rays onto a first set of pixels 41 of an image sensor array 1033
and a second optical assembly 20 focuses imaging light rays onto a
second set of pixels 42 of the image sensor array 1033. Indicia
reading terminal 1000 can be adapted to process image data
corresponding to pixels of the image sensor array 1033 for
attempting to decode a decodable indicia.
[0024] In the exemplary embodiment the first and second optical
assemblies can have different characteristics. In one aspect the
first and second optical assemblies can have different
characteristics in terms of their folding of a center optical axis.
In another aspect the first and second optical assemblies can have
different focal lengths. In yet another aspect the first and second
optical assemblies can have different best focus distances so that
the first optical assembly 10 provides optimal focusing at a first
terminal to target distance and the second optical assembly 20
provides optimal focusing at a second best focus distance.
[0025] A hardware platform suitable for supporting operational
aspects of an indicia reading terminal described herein is
described with reference to FIG. 2. Indicia reading terminal 1000
can include an image sensor 1032 comprising a multiple pixel image
sensor array 1033 having pixels arranged in rows and columns of
pixels, associated column circuitry 1034 and row circuitry 1035.
Associated with the image sensor 1032 can be amplifier circuitry
1036, and an analog to digital converter 1037 which converts image
information in the form of analog signals read out of image sensor
array 1033 into image information in the form of digital signals.
Image sensor 1032 can also have an associated timing and control
circuit 1038 for use in controlling e.g., exposure periods of image
sensor 1032, and gain applied to the amplifier circuitry 1036. The
noted circuit components 1032, 1036, 1037, and 1038 can be packaged
into a common image sensor integrated circuit 1040. In one example,
image sensor integrated circuit 1040 can be provided by a CMOS
image sensor integrated circuit. In another example, image sensor
integrated circuit 1040 can incorporate a Bayer pattern filter. In
such an embodiment, CPU 1060 prior to subjecting a frame to further
processing can interpolate pixel values intermediate of green pixel
values for development of a monochrome frame of image data. Image
sensor integrated circuit 1040 can also include a filter element
defining color sensitive pixel elements dispersed throughout an
array of monochrome pixels.
[0026] A top view of an image sensor array 1033 is shown in FIG. 3.
Image sensor array 1033 can include first set of pixels 41 onto
which light transmitted by first optical assembly 10 is incident
and second set of pixels 42 onto which light transmitted by second
optical assembly 20 is incident. First set of pixels 41 can
comprise the pixels of more than 50% of the rows of pixels of array
1033, and second set of pixels 42 can comprise the pixels of less
than 50% of the rows of pixels of array 1033. In another
embodiment, first set of pixels 41 can comprise about 60% of the
rows of pixels of array 1033, and second set of pixels 42 can
comprise about 40% of the rows of pixels of array 1033. In another
embodiment, first set of pixels 41 can comprise about 75% of the
rows of pixels of array 1033, and second set of pixels 42 can
comprise about 25% of the rows of pixels of array 1033 as is shown
in FIG. 3. A particular embodiment of image sensor array 1033 that
is divided into a first set of pixels 41 and a second set of pixels
42 is summarized herein below in Table 1.
TABLE-US-00001 TABLE 1 Pixel Size: 0.0058 mm square Active array
matrix: 838 H by 640 V Active array size: 4.8604 mm .times. 3.712
mm 1D array matrix: 838 H by 160 V 1D array size: 4.8604 mm .times.
0.928 mm 2D array matrix: 838 H by 480 V 2D array size: 4.8604 mm
.times. 2.784 mm Separation 1D & 2D areas 1.856 mm
[0027] In the course of operation of terminal 1000 image signals
can be read out of image sensor 1032, amplified by amplifier 1036,
converted by analog to digital converter 1037 and stored into a
system memory such as RAM 1080. A set of image data corresponding
to pixels of image sensor array 1033 can be regarded as a frame of
image data. A memory 1085 of terminal 1000 can include RAM 1080, a
nonvolatile memory such as EPROM 1082 and a storage memory device
1084 such as may be provided by a flash memory or a hard drive
memory. In one embodiment, terminal 1000 can include CPU 1060 which
can be adapted to address and read out image data stored in memory
1080 and subject such image data to various image processing
algorithms. Terminal 1000 can include a direct memory access unit
(DMA) 1070 for routing image information read out from image sensor
1032 that has been subject to amplification and conversion to RAM
1080. In another embodiment, terminal 1000 can employ a system bus
1500 providing for bus arbitration mechanism (e.g., a PCI bus) thus
eliminating the need for a central DMA controller. A skilled
artisan would appreciate that other embodiments of the system bus
architecture and/or direct memory access components providing for
efficient data transfer between the image sensor 1032 and RAM 1080
are within the scope and the spirit of the invention.
[0028] Terminal 1000 can be operative so that terminal 1000 can
capture a succession of frames by storage of the frames in memory
1080 where the frames are addressable for processing by CPU 1060.
Terminal 1000 can be operative so that the capture and/or
processing of the succession of frames is responsive to activation
of a trigger signal. Terminal 1000 can be operative so that such
trigger signal can be activated when an operator actuates a trigger
of terminal 1000.
[0029] As illustrated in FIG. 2 and as described further herein,
terminal 1000 can include a first optical assembly 10 and a second
optical assembly 20. The first optical assembly 10 can have an
imaging lens 12 and a center optical axis 15 and the second optical
assembly 20 can include an imaging lens 22, center optical axis 25
and a prism 32 for folding the center optical axis 25 of the second
optical assembly 20. First optical assembly 10 together with image
sensor array 1033 can define an associated first field of view 13
on a target substrate 50 and second optical assembly 20 can define
an associated second field of view 23 on a target substrate 50.
[0030] Terminal 1000 can also include an illumination pattern light
source bank 606 for use in projecting an illumination pattern 60 on
target substrate 50 and an aiming pattern light source bank 618 for
use in projecting pattern 70 on substrate 50. Each of bank 606 and
bank 618 can include one or more light sources. Terminal 1000 can
include shaping optics 607, 619 for shaping light from light source
banks 606 and 618, respectively, so that light from banks 606 and
618 can be projected into the aforementioned pattern 60 and pattern
70 respectively. In use, terminal 1000 can be oriented by an
operator with respect to a substrate 50 bearing decodable indicia
115 in such manner that aiming pattern 70 is projected on a
decodable indicia 115, that can be disposed on a target substrate
50. In the example of FIG. 2, decodable indicia 115 is provided by
a 1D bar code symbol. Decodable indicia could also be provided by
2D bar code symbols or optical character recognition (OCR)
characters. Each of illumination pattern light source bank 606 and
aiming pattern light source bank 618 can include one or more light
sources. Illumination assembly control circuit 1220 can send
signals to illumination pattern light source bank 606 e.g., for
changing a level of illumination output by illumination pattern
light source bank 606. The combination of light source bank 606 and
shaping optics 607 for shaping light from bank 606 for projecting
pattern 60 can be regarded as an illumination pattern generator.
The combination of illumination light source bank 618 and shaping
optics 619 for shaping light from bank 618 for projecting pattern
70 can be regarded as an aiming pattern generator. In addition to
or as an alternative to having an aiming pattern generator provided
by the combination of light source bank 618 and shaping optics 619,
terminal 1000 can have an aiming pattern generator provided by the
combination of light source bank 620 and shaping optics 621.
[0031] Terminal 1000 can also include a number of peripheral
devices such as display 1304 for displaying such information as
image frames captured with use of terminal 1000, keyboard 1404,
pointing device 1406 for control of a user interface cursor
displayed on display 1304, and trigger 1408 which may be used to
make active a trigger signal for activating frame readout and/or
certain decoding processes. Terminal 1000 can be adapted so that
activation of trigger 1408 activates a trigger signal and initiates
a decode attempt. Terminal 1000 can be operative so that subsequent
to activation of a trigger signal for a time that the trigger
signal remains active, terminal 1000 captures into a memory e.g.,
memory 1080 a succession of frames of image data and subjects one
or more of the captured frames to a decode attempt. Terminal 1000
can be adapted so that memory 1080 stores one or more frames of
image data therein at a time. Memory 1080 can be capable of storing
a frame of a succession of frames therein. When a frame of a
succession of frames is stored in memory 1080, the frame can be
addressed by CPU 1060 for subjecting the frame to decoding
processing for attempting to decode the frame for decodable
indicia.
[0032] Terminal 1000 can include various interface circuits for
coupling various of the peripheral devices to system address/data
bus (system bus) 1500, for communication with CPU 1060 also coupled
to system bus 1500. Terminal 1000 can include interface circuit
1028 for coupling image sensor timing and control circuit 1038 to
system bus 1500, interface circuit 1218 for coupling illumination
assembly control circuit 1220 to system bus 1500, interface circuit
1302 for coupling display 1304 to system bus 1500, and interface
circuit 1402 for coupling keyboard 1404, pointing device 1406, and
trigger 1408 to system bus 1500.
[0033] In a further aspect, terminal 1000 can include one or more
I/O interfaces 1604, 1606 for providing communication with external
devices (e.g., a cash register server, a store server, an inventory
facility server, a peer terminal 1000, a local area network base
station, a cellular base station). I/O interfaces 1604, 1606 can be
interfaces of any combination of known computer interfaces, e.g.,
Ethernet (IEEE 802.3), USB, IEEE 802.11, Bluetooth, CDMA, GSM.
[0034] Terminal 1000 can capture frames of image data at a rate
known as a frame rate. A typical frame rate is 60 frames per second
(FPS) which translates to a frame time (frame period) of 16.6 ms.
Another typical frame rate is 30 frames per second (FPS) which
translates to a frame time (frame period) of 33.3 ms per frame.
[0035] CPU 1060, appropriately programmed can carry out a decoding
process for attempting to decode a frame of image data. Terminal
1000 can be operative so that CPU 1060 for attempting to decode a
frame of image data can address image data of a frame stored in RAM
1080 and can process such image data. For attempting to decode, CPU
1060 can sample image data of a captured frame of image data along
a sampling path, e.g., along a first sampling path through a first
set of pixel positions corresponding to a first set of pixels 41
and along a second sampling path through a second set of pixel
positions corresponding to a second set of pixels 42. Next, CPU
1060 can perform a second derivative edge detection to detect
edges. After completing edge detection, CPU 1060 can determine data
indicating widths between edges. CPU 1060 can then search for
start/stop character element sequences and if found, derive element
sequence characters, character by character by comparing with a
character set table. For certain symbologies, CPU 1060 can also
perform a checksum computation. If CPU 1060 successfully determines
all characters between a start/stop character sequence and
successfully calculates a checksum (if applicable), CPU 1060 can
output a decoded message. Where a decodable indicia representation
is a 2D bar code symbology, a decode attempt can comprise the steps
of locating a finder pattern using a feature detection algorithm,
locating scan lines intersecting the finder pattern according to a
predetermined relationship with the finder pattern, determining a
pattern of dark and light cells along the scan lines, and
converting each light pattern into a character or character string
via table lookup.
[0036] It has been noted that terminal 1000 can be operative so
that subsequent to activation of a trigger signal, terminal 1000
can capture a succession of frames and subject one or more of the
captured frames to a decode attempt. A succession of frames of
image data that can be captured and subject to the described
decoding processing can be full frames (including pixel values
corresponding to more than about 80% of pixels of image sensor
1032). A succession of frames of image data that can be captured
and subject to the described processing (e.g., processing for
attempting to decode) can also be "windowed frames" comprising
pixel values corresponding to less than about 80%, and in some
cases less than about 50%, and in some cases less than 10% of
pixels of image sensor 1032. A succession of frames of image data
that can be captured and subject to the described processing can
also comprise a combination of full frames and windowed frames. A
full frame can be captured by selectively addressing for readout
pixels of image sensor 1032 corresponding to the full frame. A
windowed frame can be captured by selectively addressing for
readout pixels of image sensor 1032 corresponding to the windowed
frame.
[0037] Referring again to the diagram of FIG. 1, further aspects
and advantages of the exemplary embodiment of FIG. 1 are further
described. As shown in FIG. 1 first optical assembly 10 can have
optical characteristics differentiated from second optical assembly
20. First optical assembly 10 can include a multiple element
imaging lens 12 (shown as being provided by a triplet lens) which
transmits imaging light rays about center optical axis 15 in such
manner that in the embodiment shown center optical axis 15 is
essentially unfolded along its length and passes essentially
normally through image sensor array 1033 provided on image sensor
integrated circuit chip 1040 and extending across an imaging plane
1041. First optical assembly 10 in the embodiment shown is
essentially unfolded.
[0038] Second optical assembly 20 on the other hand is folded in
the example illustrated. In the particular example shown second
optical assembly 20 includes a multiple element imaging lens 22 (a
triplet lens in the embodiment shown) and a double folding prism
32, which folds a center axis 25 of second optical assembly 20. In
the particular embodiment shown, surface 34 of prism 32 produces a
first fold in center axis 25 of about 86.8 degrees and surface 36
of prism 32 produces a second fold in center axis 25 of about 86.8
degrees and causes center axis 25 be directed to image sensor array
1033. In one embodiment, center optical axis 25 can be directed at
image sensor array 1033 at an angle of about zero degrees relative
to normal. In another embodiment, center optical axis 25 can be
directed at image sensor array 1033 at an angle of about ten
degrees relative to normal. In another embodiment, center optical
axis 25 can be directed at image sensor array 1033 at an angle of
about twelve degrees from normal. In another embodiment, center
optical axis 25 can be directed at image sensor array 1033 at a
certain angle of between zero degrees and fifteen degrees from
normal. In one embodiment, first optical assembly 10 and second
optical assembly 20 can be adapted so that the respective best
focus distances and focal lengths of imaging lens 12 and imaging
lens 22 are fixed.
[0039] A perspective exploded view of imaging module 600 in one
embodiment is shown in FIG. 4. Referring to the view of FIG. 4,
image sensor integrated circuit 1040 can be disposed on printed
circuit board 602. Support 604 for mounting on printed circuit
board 602 can support various components such as LEDs 606 which
form an illumination light source bank in the embodiment of FIG. 4,
double folding prism 32, imaging lens 12 disposed in barrel 14,
imaging lens 22 disposed in barrel 24, aiming pattern light source
bank 618, and optics 619 for shaping light from light source bank
for projection of an aiming pattern 70. In the embodiment of FIG.
4, aiming pattern light source bank 618 is provided by a plurality
of LEDs as shown in FIG. 4. An illumination pattern shaping optics
(not shown in FIG. 4) for shaping light from light source bank 606
into pattern 60, can be mounted to an internal sidewall of a
housing 11 of terminal 1000. As an addition to having or as an
alternative to having the aiming pattern generator provided by bank
618 and optics 619, terminal 1000 can have an aiming pattern
generator in accordance with that shown in FIG. 4 provided by light
source bank 620 in combination with shaping optics 621 for
projection of an aiming pattern 70. Light source bank 620 in the
particular embodiment of FIG. 4 is provided by a laser diode
assembly. Regarding the laser diode assembly of the embodiment of
FIG. 4, the laser diode assembly forming an aiming light source
bank 620 can be disposed on printed circuit board 602. FIG. 5 shows
an assembled view of the module of FIG. 4. A perspective view of a
hand held housing 11 supporting various components as shown in the
block diagram of FIG. 5 and which can encapsulate the imaging
module of FIGS. 4-5, including image sensor array 1033, is shown in
FIG. 6.
[0040] A number of advantages are exhibited by the design in the
aspects thusfar described. By being devoid of folding optics first
optical assembly 10 is of minimal complexity and can be
manufactured at reduced cost using a reduced number of components.
Because of its reduced number of optical surfaces optical assembly
10 relative to an alternative assembly having folding optics
produces a reduced level of optical distortion and increased light
energy throughput. By its arrangement so that center optical axis
15 of first optical assembly 10 extends essentially normally from
image plane 1041, optical assembly 10 focuses images onto image
sensor array 1033 that are essentially devoid of keystone
distortion.
[0041] Keystone distortion is produced when a center axis of a
focusing optical assembly extends at an angle with respect to an
image plane. An image representation of a square exhibiting
keystone distortion takes on the shape of a keystone having top and
bottom edges of unequal width and connecting first and second side
edges that are in non-parallel relation to one another, and which
extend at non-normal angles from the top and bottom edges. Decoding
decodable indicia representations that exhibit significant keystone
distortion can be challenging, especially for certain types of
indicia. Relative to decoding bar code symbols having no keystone
distortion, keystone distorted bar code symbol representations
generally require longer decoding times and increased decoding
algorithm complexity. Providing an optical system that increases
the incidence of frames captured having little or no keystone
distortion increases decoding efficiency.
[0042] Referring to second optical assembly 20, second optical
assembly 20 is also advantageously configured. While double folding
prism 32 of second optical assembly 20 can produce distortion not
encountered if prism 32 is deleted, the introduction of folding
optics into optical assembly 20 provides various advantages. One
advantage provided by the introduction of folding optics into
second optical assembly 20 is that utilization of a relatively
smaller image sensor chip 1040 with relatively large scale optical
components is facilitated. One of the largest cost factors of an
indicia reading terminal 1000 is the cost of image sensor
integrated circuit (chip) 1040 on which image sensor array 1033 is
disposed. In general, costs of image sensor chip 1040 are kept
small if of a mass produced sized. Generally mass produced
relatively low cost image sensor chips are of relatively small
dimensions (the image sensor array of an exemplary image sensor
chip has an imaging area of 4.86 mm.times.3.71 mm). Further
referring to advantages of optical assembly 20, the design of prism
32 in the particularly highlighted embodiment provides various
advantages. While double folding prism 32 produces a fold at a
center axis 25 of second optical assembly 20, it is seen that
double folding prism 32 nevertheless directs center axis 25 of
second imaging assembly 20 toward imaging plane 1041 at a near
normal angle. Accordingly, image representations that are stored by
terminal 1000 corresponding to second set of pixels 42 will be
relatively free of keystone distortion and therefore relatively
easy to decode as compared to frames exhibiting significant
keystone distortion.
[0043] In an alternative embodiment, double folding prism 32 as
shown in FIG. 1 can be replaced with a set of first and second
mirrors disposed respectively at the locations of first and second
surfaces 34 and 36. However, relative to a mirror design, the
inventors determined that a double folding prism design in
accordance with prism 32 provides certain advantages. Prism 32
shown in perspective view of FIG. 7 can be formed by a process of
injection molding using a mold form or else by a process of optical
grinding. By either method, the angle between surface 34 and
surface 36 can be precisely controlled. In one embodiment, an angle
between surfaces 34 and 36 can be controlled so that surfaces 34
and 36 are parallel to one another. In another embodiment, the
surfaces 34 and 36 can be controlled so that surfaces 34 and 36 are
in a predetermined but non-parallel (e.g., a near parallel)
relationship to one another. More particularly, with reference to
FIG. 7, the angle between surface 34 and surface 36 can be
precisely controlled by way of precision injection molding or
optical grinding process. The providing of double folding prism 32
which can be manufactured by a precision manufacturing process
including e.g., injection molding or grinding, reduces
manufacturing costs and process steps e.g., a step including
precision molding and alignment of a mirror system. Also, double
folding prism 32 can be readily manufactured to be highly durable.
By contrast, an alternative mirror design can readily become
misaligned or damaged when terminal 1000 is dropped or otherwise
subject to contact with a rigid surface. In one embodiment, double
folding prism 32 can comprise a unitary piece of polycarbonate
material.
[0044] The design thusfar described having a first optical assembly
that is essentially unfolded and including a center axis that is
essentially free of folds and a second optical assembly that is
folded exhibits the package size reduction advantages yielded by a
folding system, yet provides an optical path that yields
performance advantages of an unfolded system.
[0045] Referring to further aspects of terminal 1000, first optical
assembly 10 can have a first best focus distance and second optical
assembly 20 have a second best focus distance that is different
from the first best focus distance. Configuring assemblies 10 and
20 to have different best focus distances increases a working range
of terminal 1000. For example, in one embodiment optical assembly
10 can be configured to have a short range best focus distance of
130 mm and second optical assembly 20 can be configured to have a
long range best focus distance of 420 mm. Thus, a target substrate
having decodable indicia that is too far away to be adequately
focused by first optical assembly 10 may nevertheless be
successfully focused by second optical assembly 20.
[0046] In another advantageous aspect, terminal 1000 can be
configured so that first optical assembly 10 and second optical
assembly 20 can have different focal lengths. Configuring first
optical assembly 10 and second optical assembly 20 to have
different focal lengths provides significant advantages. In one
particularly advantageous example, imaging lens 22 of second
optical assembly 20 can be configured to have a relatively longer
focal length than near focused imaging lens 12 of first optical
assembly 10. A field of view, O, of an optical system along a
horizontal or vertical axis can be expressed by:
O = I ( p - f ) f Equation 1 ##EQU00001##
[0047] Where I is the width of the image sensor array 1032 along
the horizontal axis (or height along a vertical axis), p is the
object (e.g., target substrate 50) to imaging lens distance, and f
is the focal length of the imaging lens. Accordingly, it can be
seen that for two optical assemblies at a given distance from a
target, an optical assembly having a longer focal length will
provide a narrower field of view. In one example, terminal 1000 can
be configured so that second optical assembly 20 has a relatively
larger focal length than first optical assembly 10.
[0048] Such a configuration is advantageous for a number of
reasons. At longer reading distances a narrow field of view
prevents there from being represented in a frame captured for
decoding processing extraneous decodable indicia (e.g., on a
shipping box other than the one of interest) that the user has no
interest in decoding, and if subject to processing can
unnecessarily consume processing time. Also, the narrow field of
view at a long range focus distance provides for capture of high
resolution (in terms of pixels per bar) frames for processing. In
one example, two pixel samples (in the form of gray scale pixel
values) are obtained per narrow bar or space element.
[0049] It has been noted that advantages are provided by a design
having a first optical assembly that is essentially or minimally
unfolded and a second folded optical assembly, and by designing one
of the optical assemblies to have a longer focal length than the
other. The inventors further determined that further advantages can
be provided by selection of the longer focal length optical
assembly (second assembly 20 in the example illustrated) as the
assembly to include a folded center axis and the corresponding
selection of the shorter focal length optical assembly (first
assembly 10 in the example illustrated) as the assembly for
inclusion of an essentially unfolded or minimally folded center
optical axis. Namely, such selection provides significant packaging
and miniaturization advantages. For optimal focusing of an image
onto an image plane, the image plane must be spaced from an imaging
lens at a lens to image plane distance of at least the focal
length. As the long focal length imaging lens (imaging lens 22 in
the example illustrated) requires relatively longer spacing from an
image plane for achievement of optimal focusing the inclusion of
folding optical prism 32 in second optical assembly 20 provides the
appropriate spacing between lens 22 and plane 1041 yet without
increasing the space requirements of module 600 along the Z axis.
(Reference plane indicated in FIG. 1.)
[0050] Referring now further to advantages of the selected folded
optical path for optical assembly 20, the folded design of second
optical assembly 20 can also prevent a light blocking problem which
might otherwise be encountered. The inventors determined, as has
been described herein, that advantages may be yielded by selection
of a relatively longer focal length for second optical assembly 20.
The inventors also determined that if imaging lens 22 of second
optical assembly 20 is spaced at a long distance from array 1033
relative to lens 12 in an alternative scheme where optical axis 15
and axis 25 are unfolded and in continuous parallel relation,
imaging lens 12 can block light rays transmitted by lens 22 from
reaching array 1033. Accordingly, another advantage of the
selection of a folding optical system for second assembly 20 is
that such selection prevents the described light blocking effect.
Optical system data of the imaging module of FIG. 1 in one
particular embodiment is summarized in Table 2 (first optical
assembly 10) and in Table 3 (second optical assembly 20) below.
TABLE-US-00002 TABLE 2 Lens Structure air spaced triplet Effective
Focal Length 5.88 mm Paraxial F/# 6.9 Image size 4.8604 mm .times.
2.784 mm Plane of nominal focus 130 mm System FOV (full width) at
96 mm .times. 55 mm nominal focus
TABLE-US-00003 TABLE 3 Lens Structure air spaced triplet Effective
Focal Length 11.8 mm Paraxial F/# 6.7 Image size 4.8604 mm .times.
0.928 mm Plane of nominal focus 420 mm System FOV (full width) at
169 mm .times. 32 mm nominal focus
[0051] In arriving at a particularized version of the design shown
in FIG. 1, the inventors recognized that while 1D bar code symbols
are commonly encountered at long reading range distances, 2D bar
code symbols are more commonly encountered at short range. For
example, while shipping packages often located at longer terminal
distances on shelves typically include a clustering of 1D bar code
symbols, 2D bar code symbols are more commonly found on close range
accessible objects such as identification cards and documents.
[0052] In another aspect of terminal 1000, terminal 1000 can be
configured so that terminal 1000 is optimized for decoding 2D bar
code symbols utilizing image data corresponding to a first set of
pixels representing light transmitted through first optical
assembly 10 and incident on first set of pixels and/or and be
further configured so that terminal 1000 can be optimized for
decoding 1D symbols utilizing image data corresponding to second
set of pixels and representing light transmitted through second
optical assembly 20 and incident on second set of pixels. 1D bar
code symbols include UPC, Code 39 and Code 128. 2D bar code symbols
include Datamatrix, QR Code, Aztec, and PDF 417. Terminal 1000 can
be adapted so that a level of optimization for decoding 2D bar code
symbols is higher when terminal 1000 processes image data
representing light incident on first set of pixels 41 that has been
transmitted by assembly 10 relative to when terminal 1000 processes
image data representing light incident on second set of pixels 42
transmitted by second optical assembly 20.
[0053] In one embodiment of such an optimization scheme, terminal
1000 can be configured so that terminal 1000 can utilize each of N
2D bar code symbol decoding algorithms when processing image data
representing light incident on first set of pixels 41, and further
so that terminal 1000 is restricted from utilizing a subset of
decoding algorithms of the set of N 2D decoding algorithms when
processing image data corresponding to pixels of the second set 42
for decoding. In another embodiment of an optimization scheme,
terminal 1000 can be restricted from applying any 2D bar code
symbol decoding algorithm when processing frame image data
corresponding to pixels of the second set 42 for decoding.
[0054] In another aspect of a 1D/2D optimization scheme described,
terminal 1000 can be configured so that images projected by the
first optical assembly 10 are focused on a larger percentage of
pixels of images sensor array 1033 than are images projected by
optical assembly 20. In one embodiment, first optical assembly 10
can be adapted to focus a target substrate image on more than 50%
of pixels of image sensor array 1033, and second optical assembly
20 can be adapted to focus a target substrate image on less than
50% of pixels of image sensor array 1033. In a particular
embodiment, first optical assembly 10 can be adapted to focus a
target substrate image on about 60% of pixels of array 1033 and
second optical assembly 20 is configured to focus a target image on
about the remaining 40% of the pixels of array 1033. In another
embodiment, first optical assembly 10 can be adapted to focus a
target substrate image on 75% of pixels of array 1033 and second
optical assembly 20 can be adapted to focus a target substrate
image on the remaining 25% of pixels of array 1033. The described
pixel sharing ratio aspect of a 1D/2D optimization scheme
recognizes that 1D bar code symbols can often be readily decoded by
processing of image data corresponding to limited number of rows
(or columns), and possibly a single row (or column) of pixels of an
image sensor array 1033.
[0055] Referring to further aspects of imaging module 600, imaging
module 600 can be adapted so that light from aiming pattern light
source bank 618 is projected at a specific location with respect to
a target substrate 50 on which fields of view 13 and 23 can be
defined. FIG. 8 illustrates respective fields of view 13 and 23
defined by first optical assembly 10 and second optical assembly
20, respectively, at various terminal to target distances ranging
from a short range distance of about 130 mm to a long range
distance of about 420 mm. FIG. 8 illustrates the relative fields of
view 13 and 23 at a relatively shorter terminal to target distance
e.g., 130 mm through a relatively longer terminal to target
distance e.g., 420 mm. Terminal 1000 can be adapted so that field
of view 23 is defined within field of view 13 through a range of
terminal to target distances as is illustrated in FIG. 8. As seen
from FIG. 8 corresponding to an optical system in accordance with
that generally described with reference to FIG. 1, the field of
view 13 defined by first optical assembly 10 in combination with
image sensor array 1033, at a given terminal to target distance, is
relatively larger than field of view 23 defined by second optical
assembly 20 in combination with image sensor array 1033. Also, as
is illustrated by FIG. 8, field of view 23 can be defined at a
location within a field of view 13 through a range of terminal to
target distances ranging from a short range distance of about 130
mm to a long range distance of about 420 mm. Further, while field
of view 23 moves closer to the upper border of field of view 13 at
shorter terminal to target distances, and while the field of view
moves closer to and can encompass horizontally extending centerline
19 at longer terminal to target distances, the actual distance, d,
between the horizontally extending centerlines 19 and 29 of the
respective fields of view 13, 23 remains a constant distance, d,
all throughout the full range of terminal to target distances. In
one embodiment, terminal 1000 can be adapted so that the aiming
pattern generator provided by light source bank 618 in combination
with optics 619 projects an aiming pattern 70 as is shown in FIGS.
9 and 10. In the embodiment described in connection with FIGS. 9
and 10, the aiming pattern generator provided by bank 618 and
optics 619 projects an aiming pattern that is projected
substantially at a horizontally extending centerline 19 of first
field of view 13 through a range of terminal to target distances
ranging from a short range distance of about 130 mm to a long range
distance of about 420 mm. It has been noted that at longer terminal
to target distances, field of view 23 can approach and can
encompass horizontally extending centerline 19 of field of view 13.
Accordingly, adapting terminal 1000 to project an aiming pattern 70
at horizontally extending centerline 19 provides good aiming and a
range of terminal to target distances which range in one embodiment
can include a shorter range distance of about 130 mm through a long
range distance of about 420 mm. According to one embodiment as is
described with reference to FIGS. 11 and 12, terminal 1000 can
include an aiming pattern generator adapted so that aiming pattern
70 is projected substantially on horizontally extending centerline
29 of field of view 23 throughout the range of terminal to target
distances (e.g., from a short, e.g., 130 mm to a long, e.g., 420 mm
distance). Recognizing that aiming pattern 70 will, through a range
of terminal to target distances be projected within field of view
13 where terminal 1000 is adapted so that field of view 23 is
defined within field of view 13 through a range of terminal to
target distances, and where terminal 1000 is adapted so that
pattern 70 is projected at a substantially fixed position within
field of view 23, the projecting of aiming pattern 70 at a
horizontally extending centerline 29 of field of view 23 throughout
a range of terminal to target distances (e.g., from a short range
of 130 mm to a long range of about 420 mm) provides high quality
aiming throughout the full range of terminal to target distances.
The arrangement described can be particularly advantageous in the
case as described with reference to FIG. 1 where second assembly 20
has a longer best focus distance and longer focal length that first
optical assembly 10. An aiming pattern generator for generating
aiming pattern 70 as shown in FIGS. 11 and 12 can be provided by,
e.g., light source bank 620 provided by a laser diode assembly in
combination with shaping optics 621 as is shown in the imaging
module of FIG. 1.
[0056] In one embodiment, terminal 1000 can include a single aiming
pattern generator that projects aiming pattern 70 at a horizontally
extending centerline 19 of field of view 13 through a range of
terminal to target distances as shown in FIGS. 9 and 10. In one
embodiment, terminal 1000 can include a single aiming pattern
generator that projects aiming pattern 70 as a horizontally
extending centerline 29 of field of view 23 as shown in FIGS. 11
and 12.
[0057] In yet another embodiment, terminal 1000 can include first
and second aiming pattern generators for projecting each of an
aiming pattern 70 substantially at horizontally extending
centerline 19 through a range of terminal to target distances and
aiming pattern 70 substantially at horizontally extending
centerline 29 through a range of terminal to target distances.
Terminal 1000 in one embodiment can include a first aiming pattern
generator comprising elements 618 and 619 and a second aiming
pattern generator comprising elements 620 and 621. Terminal 1000
can be operative so that the two spaced apart patterns can be
projected simultaneously as shown in FIGS. 13 and 14.
Alternatively, terminal 1000 can be operative so that the two
patterns are projected in the alternative in a manner responsive to
a sensed condition. For example, terminal 1000 can be operative to
selectively activate a first aiming pattern 70 substantially at
horizontally extending centerline 19 at shorter terminal to target
distances (with the second aiming pattern generator being
deactivated at such terminal to target distances) and can be
operative to selectively activate a second aiming pattern generator
to project aiming pattern 70 at horizontally extending centerline
29 at longer terminal to target distances (with the first aiming
pattern generator being off at such terminal to target distances).
Terminal 1000 can be operative to sense a terminal to target
distance by reading a white level of a frame of image data, with a
higher coverage white level indicating more artificial illumination
from terminal 1000 and therefore a closer terminal to target
distance. In another embodiment as is illustrated in FIGS. 15 and
16, an aiming pattern generator, e.g., 618, 619 or generator 620,
621 can be adapted to project aiming pattern 70 at a position
intermediate of horizontally extending centerline 19 and
horizontally extending centerline 29 through a range of terminal to
target distances ranging from a short range, e.g., 130 mm to a long
range, e.g., 420 mm.
[0058] A small sample of systems methods and apparatus that are
described herein is as follows:
[0059] A1. An indicia reading terminal comprising:
[0060] a two dimensional image sensor array extending along an
image plane, said two dimensional image sensor array comprising a
plurality of pixels;
[0061] a hand held housing encapsulating said two dimensional image
sensor array;
[0062] a first optical assembly having a center optical axis and an
imaging lens, said first optical assembly for focusing imaging
light rays onto a first set of pixels of said two dimensional image
sensor array, wherein said imaging light rays transmitted by said
first optical assembly are transmitted about said center optical
axis of said first optical assembly, and wherein said first optical
assembly is adapted so that said center optical axis of said first
optical assembly is essentially unfolded;
[0063] a second optical assembly having a center optical axis and
an imaging lens, said second optical assembly for focusing imaging
light rays onto a second set of pixels of said two dimensional
image sensor array, wherein said imaging light rays transmitted by
said second optical assembly are transmitted about said center
optical axis of said second optical assembly, and wherein said
second optical assembly includes an optical surface that folds said
center optical axis of said second optical assembly by an angle of
more than 10 degrees;
[0064] a memory capable of storing a frame of image data, said
frame of image data representing light incident on said image
sensor array; and
[0065] a CPU capable of addressing said memory, wherein said CPU is
adapted to attempt to decode a decodable indicia represented in
said frame of image data.
[0066] A2. The indicia reading terminal of claim A1, wherein said
imaging lens of said first optical assembly has a shorter focal
length than said imaging lens of said second optical assembly.
[0067] A3. The indicia reading terminal of claim A1, wherein said
indicia reading terminal is adapted so that a field of view defined
by said first optical assembly in combination with said image
sensor array when said indicia reading terminal is at a certain
terminal to target distance is larger than a field of view defined
by said second optical assembly in combination with said image
sensor array when said indicia reading terminal is at said certain
terminal to target distance.
[0068] A4. The indicia reading terminal of claim A1, wherein said
first optical assembly has a shorter best focus distance than said
second optical assembly.
[0069] A5. The indicia reading terminal of claim A1, wherein said
first optical assembly has a shorter best focus distance than said
second optical assembly, wherein said first optical assembly has a
shorter focal length than said second optical assembly, and wherein
said first and second optical assemblies are fixed assemblies such
that that said best focus distances and said focal lengths of said
first and second optical assemblies are fixed.
[0070] A6. The indicia reading terminal of claim A1, wherein said
first set of pixels comprises a larger number of pixels than a
number of pixels of said second set of pixels.
[0071] A7. The indicia reading terminal of claim A1, wherein a
ratio of pixels of said first set of pixels to said second set of
pixels is greater than 1.5.
[0072] A8. The indicia reading terminal of claim A1, wherein said
second optical assembly includes a double folding prism disposed in
an optical path of said second optical assembly intermediate of
said imaging lens of said second optical assembly and said image
sensor array, the double folding prism folding said center optical
axis of said second optical assembly in at least two locations,
said double folding prism being adapted so that said center optical
axis of said second optical assembly extends from said image sensor
array at an angle that deviates from a normal angle by less than 10
degrees.
[0073] A9. The indicia reading terminal of claim Al, wherein said
second optical assembly includes a double folding prism disposed in
an optical path of said second optical assembly intermediate of
said imaging lens of said second optical assembly and said image
sensor array, the double folding prism having at least two
reflective surfaces for bending said center optical axis of said
second optical assembly, said double folding prism being formed
utilizing one of a precision molding process and a precision
grinding process.
[0074] A10. The indicia reading terminal of claim A1, wherein said
indicia reading terminal is capable of processing image data of
said certain frame for attempting to decode a 2D bar code symbol
representation, and wherein said indicia reading terminal is
operative so that a level of optimization for decoding of a 2D bar
code symbol representations is greater when said CPU processes
image data representing light incident on said first set of pixels
than when processing image data representing light incident on said
second set of pixels.
[0075] A11. The indicia reading terminal of claim A10, wherein said
indicia reading terminal is restricted from operating according to
an algorithm for attempting to decode a 2D bar code symbol when
processing image data corresponding to said second set of
pixels.
[0076] A12. The indicia reading terminal of claim A1, wherein said
first optical assembly defines with said image sensor array a first
field of view, wherein said second optical assembly defines with
said image sensor array a second field of view, and wherein said
indicia reading terminal is adapted so that said indicia reading
terminal projects an aiming pattern at a substantially fixed
location in relation to said second field of view though a range of
terminal to target distances ranging from a short range terminal to
target distance of about 130 mm to a long range terminal to target
distance of about 420 mm.
[0077] A13. The indicia reading terminal of claim A1, wherein said
first optical assembly defines with said image sensor array a first
field of view and wherein said second optical assembly defines with
said image sensor array a second field of view, and wherein said
indicia reading terminal is adapted so that said indicia reading
terminal projects an aiming pattern substantially at a horizontally
extending centerline of said second field of view though a range of
terminal to target distances ranging from a short range terminal to
target distance of about 130 mm to a long range terminal to target
distance of about 420 mm.
[0078] A14. The indicia reading terminal of claim A1, wherein said
indicia reading terminal is adapted so that said first set of
pixels includes a set of pixels extending across more than 50% of
the rows of said image sensor array and wherein said second set of
pixels includes a set of pixels extending across less than 50% of
rows of pixels of said pixels of image sensor array.
[0079] A15. The indicia reading terminal of claim A1, wherein said
second optical assembly includes an optical surface that folds said
center optical axis of said second optical assembly by more than 30
degrees.
[0080] A16. The indicia reading terminal of claim A1, wherein said
indicia reading terminal includes aiming pattern generator that
projects an aiming pattern substantially at a horizontally
extending centerline of a field of view defined by said first
optical assembly in combination with said image sensor array
through a range of terminal to target distances ranging from about
130 mm to 420 mm.
[0081] A17. The indicia reading terminal of claim A1, wherein said
indicia reading terminal wherein said first optical assembly and
said image sensor array define a first field of view, and wherein
said second optical assembly and said image sensor array define a
second field of view, and wherein said terminal includes a first a
first aiming pattern generator and a second aiming pattern
generator, the first aiming pattern generator capable of projecting
an aiming pattern substantially at a horizontally extending
centerline of said first field of view through a range of terminal
to target distances, the second aiming pattern generator capable of
projecting an aiming pattern substantially at a horizontally
extending centerline of said second field of view through a range
of terminal to target distances.
[0082] A18. The indicia reading terminal of claim A17, wherein said
terminal is operative so that at least one of said first and second
aiming pattern generators is activated responsively to a sensed
condition.
[0083] A19. The indicia reading terminal of claim A1, wherein said
first optical assembly and said image sensor array define a first
field of view and wherein said second optical assembly and said
image sensor array define a second field of view, and wherein said
terminal includes an aiming pattern generator that projects an
aiming pattern substantially at a horizontally extending centerline
of said second field of view through a range of terminal to target
distances.
[0084] B1. An indicia reading terminal comprising:
[0085] a two dimensional image sensor array extending along an
image plane, said two dimensional image sensor array comprising a
plurality of pixels;
[0086] a hand held housing encapsulating said two dimensional image
sensor array;
[0087] a first optical assembly defining in combination with said
image sensor array a first field of view, said first optical
assembly having a center optical axis and an imaging lens, the
first optical assembly for focusing imaging light rays onto a first
set of pixels of said two dimensional image sensor array, said
first set of pixels comprising more than 50% of pixels of said
image sensor array, wherein said imaging light rays transmitted by
said first optical assembly are transmitted about said first center
optical axis of said first optical assembly, and wherein said first
optical assembly is adapted so that said first center optical axis
is essentially unfolded;
[0088] a second optical assembly defining in combination with said
image sensor array a second field of view, said second optical
assembly having a center optical axis and an imaging lens, the
second optical assembly for focusing imaging light rays onto a
second set of pixels of said two dimensional image sensor array,
said second set of pixels comprising less than 50% of pixels of
said image sensor array, wherein said imaging light rays
transmitted by said second optical assembly are transmitted about
said center optical axis of said second optical assembly, and
wherein said second optical assembly includes an optical element
that folds said center optical axis of said second optical assembly
by an angle of more than 10 degrees, said second optical assembly
having a longer best focus distance than said first optical
assembly, said imaging lens of said second optical assembly having
a longer focal length than said imaging lens of said first optical
assembly;
[0089] an aiming pattern generator including a laser diode
assembly, said aiming pattern generator projecting an aiming
pattern;
[0090] a memory capable of storing a frame of image data, said
frame of image data having image data representing light incident
on said image sensor array; and
[0091] a CPU capable of addressing said memory, wherein said CPU is
adapted to attempt to decode a decodable indicia represented in
said frame of image data.
[0092] B2. The indicia reading terminal of claim B1, wherein said
aiming pattern generator is adapted to project said aiming pattern
substantially at a horizontally extending centerline of said second
field of view through a range of terminal to target distances.
[0093] C1. An indicia reading terminal comprising:
[0094] a two dimensional image sensor array extending along an
image plane, said two dimensional image sensor array comprising a
plurality of pixels;
[0095] a hand held housing encapsulating said two dimensional image
sensor array;
[0096] a first optical assembly having a center optical axis and an
imaging lens, said first optical assembly for focusing imaging
light rays onto a first set of pixels of said two dimensional image
sensor array, wherein said imaging light rays transmitted by said
first optical assembly are transmitted about said center optical
axis of said first optical assembly;
[0097] a second optical assembly having a center optical axis and
an imaging lens, said second optical assembly for focusing imaging
light rays onto a second set of pixels of said two dimensional
image sensor array, wherein said imaging light rays transmitted by
said second optical assembly are transmitted about said center
optical axis of said second optical assembly, and wherein said
second optical assembly includes a precision manufactured double
folding prism for folding said center optical axis of said second
optical assembly at two locations, said double folding prism being
precision manufactured by one of an injection molding process or an
optical grinding process;
[0098] a memory capable of storing a frame of image data, said
frame of image data representing light incident on said image
sensor array; and
[0099] a CPU capable of addressing said memory, wherein said CPU is
adapted to attempt to decode a decodable indicia represented in
said frame of image data.
[0100] C2. The indicia reading terminal of claim C1, wherein said
first optical assembly is adapted so that said center optical axis
of said first optical assembly is essentially unfolded.
[0101] C3. The indicia reading terminal of claim C1, wherein said
second optical assembly includes a longer best focus distance and a
longer focal length than said first optical assembly, and wherein
said indicia reading terminal is adapted so that a field of view
defined by said second optical assembly and said image sensor array
is defined, throughout a range of terminal to target distances from
about 130 mm to about 420 mm, at a location within a field of view
defined by said second optical assembly and said image sensor array
throughout a range of terminal to target distances from about 130
mm to about 420 mm.
[0102] While the present invention has been described with
reference to a number of specific embodiments, it will be
understood that the true spirit and scope of the invention should
be determined only with respect to claims that can be supported by
the present specification. Further, while in numerous cases herein
wherein systems and apparatuses and methods are described as having
a certain number of elements it will be understood that such
systems, apparatuses and methods can be practiced with fewer than
the mentioned certain number of elements.
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